I'm using an earlier version (3.99) for Mac, but I would imagine the one you just purchased wouldn't be too different.
Are you working off your main computer (the one where you installed the program) or your web access? If it is the web access, you can just start typing in the description field after you click on "Add Item." If it is the main computer, you click on "Add Item" and just fill out the items in the pop up box about what you are adding.
It is easier to have a list of items that you normally sell to select from, but it is not required.
Teri